This will install all of the necessary dependencies to run Unity 2D, including a "Unity 2D" session that you'll need to login with. Then log out and when logging back in select "Unity 2D" at the bottom of the login screen.

For 11.04

This will install all of the necessary dependencies to run Unity 2D, including a "Unity 2D" session that you'll need to login with. Then log out and when logging back in select "Unity 2D" at the bottom of the login screen.

Link to "fallback session" appears to be a private message or some other thing that public users lack permissions to - please copy/paste into this answer. This appears to cover the intended material liberiangeek.net/2013/04/…
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Chris MoschiniApr 10 '14 at 22:38